(1) Field of the Invention
This invention relates to processing fibrous materials and more particularly to a brush for doffing cotton from a saw cylinder.
(2) Description of the Prior Art
In ginning cotton it is well known and the usual practice to snag the cotton upon a saw cylinder for processing and then doff the cotton from the cylinder. This process occurs typically three times in the processing of the cotton. First, the cotton is picked up a lock at a time in the early processing stages of the cotton gin to clean sticks, burrs, dirt and trash from the cotton. This is done by beating the cotton against bars. After this process the cotton is doffed by a brush cylinder by rotating at higher speed.
Thereafter in the ginning process itself, locks of cotton are picked up by the saw cylinder and then the fiber pulled through ribs which prevent the seed from going through the ribs and then the cotton doffed from the saw cylinder. Although the cotton is sometimes doffed by an air blast, it is also often doffed by a brush.
Thereafter often the cotton lint itself is picked up by a saw cylinder for lint cleaning process wherein the cotton is beat against mote bars to remove dust and trash from the lint, then it is doffed by brushes.
The brushes are mounted upon sticks. In the prior art these sticks are made of wood such as birch or hardwood. Sometimes the sticks are made from laminated wood. Holes are drilled for the individual tuffs or bundles of the fiber which are then glued and stapled in place. The bristles are natural bristles. The two most popular bristles being horsehair bristles or Tampico fiber. The Tampico Fiber is a plant fiber. The most common plant fiber used is known in the trade as "Black Patent Tampico".
The saw cylinders themselves rotate at high speed and for doffing it is necessary that the brushes move faster than the surface of the saw cylinder. Therefore, the brush cylinders turn at very high speed. It is necessary that they be balanced. With natural woods, it is extremely difficult to get the brush sticks to be of equal weight and, therefore, there is always a balancing problem. Also, in recent years there has been a greater problem in obtaining natural wood for these sticks which does not warp badly. In short, in modern practice it is difficult to find wood suitable for use in high speed precision machinery.
Another serious problem that exists in the cotton gin is that of static electricity. Many synthetic materials have a high production of static electricity. This is the main reason why natural fibers are used in the brushes rather than synthetic fibers. Also, it may have been in the prior art that the wood brush sticks were thought to be necessary to prevent an excess of static electricity.